This invention relates to a tubesheet and a method for explosively welding a tube into said tubesheet and, more particularly, to such a tubesheet and method in which a cladding is bonded to a surface of the tubesheet and is prevented from being separated therefrom.
In order to secure a plurality of heat exchange tubes in corresponding bores formed in a tubesheet, several techniques have evolved. One of the most effective techniques is to explosively force each tube against the internal wall defining the corresponding bore in the tubesheet, which involves detonating an explosive placed within the tube so that the resulting explosive forces acting on the tube expands it and forces the outer surface of the tube to the bore wall.
However, several problems exist in these types of techniques. For example, the tubesheet is often fabricated from a relatively inexpensive material, such as steel, for economic reasons and the outer surfaces of the tubesheet are often provided with a layer or cladding consisting of a relative thin layer of material which is resistant to the corrosive elements to which the tubesheet is exposed. However, the bond between steel and some cladding materials, such as titanium, aluminum and the like, are somewhat limited due to the differences in the molecular makeup between the respective materials.